Tear down and processing are going smoothly so far! We actually haven’t quite finished, as we are waiting for the soil to dry before sieving. But, we’ve done most of it. Here is a breakdown of what we’ve done so far!
First, we photographed each pot with our benthic camera, which senses the infrared wavelengths of chlorophyll pigments and makes them show up as red in the photo. This gives us a visual estimation of the amount of chlorophyll in the photo subject.
Once we had taken an above and side shot of each of the 60 pots, we set up a processing station in the wet lab. We are using multiple parameters to measure growth response in the grasses, one of which is plant height. The following photos show some of the plants and the obvious differences in growth between pots that had midges added to them (right side, “M” pots) and pots that didn’t (left side, “C” pots). The numbers on each label (1-4) represent my four precipitation levels. 1 pots received 10 ml of water, 2 got 25 ml, 3 got 35 ml, and 4 received 50 ml of water on watering days.
Another parameter we’ll be measuring is aboveground biomass. For this, we clipped the grass off at soil level, and are dry weighting them for comparison between pots.
Here, Kyle is pulling apart the soil of the pots to remove a resin bag from the center. Resin bags were placed in the pots to absorb soil nutrients. They will be taken back to the University of Wisconsin for further processing, which will tell us the amounts of nitrogen and phosphorous that accumulated in each of the pots.
Finally, in the coming days, we will be sieving the soil in order to collect the roots from each pot. The roots will be dry weighted and combusted in order to give us a measure of below ground biomass.
I really enjoyed conducting this experiment. It was interesting to see how the plants changed over the weeks, and to see how they responded to their assigned treatment. I think it was a success!